"""
Authentication Service
Handles JWT token generation, validation, and password hashing.
"""

import os
from datetime import datetime, timedelta, timezone
from jose import JWTError, jwt
import bcrypt
from dotenv import load_dotenv

load_dotenv()

SECRET_KEY = os.environ.get("JWT_SECRET_KEY")
if not SECRET_KEY:
    raise ValueError("JWT_SECRET_KEY is not set in environment")

ALGORITHM = os.environ.get("JWT_ALGORITHM")
ACCESS_TOKEN_EXPIRE_MINUTES = int(os.environ.get("JWT_ACCESS_TOKEN_EXPIRE_MINUTES"))

def verify_password(plain_password: str, hashed_password: str) -> bool:
    return bcrypt.checkpw(plain_password.encode('utf-8'), hashed_password.encode('utf-8'))

def get_password_hash(password: str) -> str:
    salt = bcrypt.gensalt()
    return bcrypt.hashpw(password.encode('utf-8'), salt).decode('utf-8')

def create_access_token(data: dict, expires_delta: timedelta | None = None) -> str:
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def decode_access_token(token: str) -> dict | None:
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload
    except JWTError:
        return None